The present invention is directed to a multiplex injector, and more particularly, to a multiplex injector having a plurality of injector tips that can be selectively controlled.
In aircraft and other engines, fuel injectors are typically used to inject fuel in a spray or atomized form into a combustion chamber of the engine. The atomized air/fuel mixture is then compressed and combusted to create the energy required to provide the engine output and sustain engine operations. Many existing engines have fixed geometry injector systems that include a plurality of injector tips that are commonly controlled to inject fuel into the combustion chamber. For example, fixed geometry injectors such as pressure swirl and air blast atomizer designs are used in aircraft, marine and industrial gas turbines. In such fixed geometry injector systems, the injectors are typically maintained in a xe2x80x9cfully openxe2x80x9d status during all stages of engine operations. Such conventional fixed geometry injector systems lack the ability to adapt to varying conditions of engine operations, which can lead to relatively high emissions and systems that lack combustion stability during certain operating conditions of the engine.
For example, pure air blast atomizers are often used as injectors and provide acceptable performance at high power conditions. However, such air blast atomizers may not provide adequate performance during start-up and low power engine conditions. Simplex air blast atomizers, such as that disclosed in U.S. Pat. No. 5,224,333 to Bretz et al., the contents of which are hereby incorporated by reference, may also perform acceptably at high power engine conditions, but may not provide sufficient mixing or sufficiently low emission levels at high power conditions.
Variable geometry injectors have also been used in an attempt to provide an injector system that can adapt to various engine conditions. However, such variable geometry injectors may include moving parts that can become clogged or stuck due to heat stress or carbon deposits formed in the injector system. Accordingly, there is a need for a robust injector system that can be dynamically controlled to adapt the injector system to varying engine conditions.
The present invention is a multiplex injector that is robust and provides a variable, controllable output spray. More particularly, the multiplex injector includes at least a first and a second set of injector tips, and fuel can be selectively routed to the first and second sets of injector tips to control the volume and pattern of fuel sprayed by the injector. The multiplex injector may include nearly any number of sets of injector tips that can be controlled in nearly any desired manner to achieve the desired performance.
In one embodiment, the invention is a multiplex injector system comprising an injector head, a first fuel path located in the injector head, and a first set of injector tips located in the injector head and in fluid communication with the first fuel path. The first set of injector tips includes at least one first injector tip. The multiplex injector further includes a second fuel path located in the injector head and a second set of injector tips located in the injector head and in fluid communication with the second fuel path. The second set of injector tips includes at least one second injector tip. A flow of fuel in each of the first and second fuel paths can be selectively controlled to control the flow of fuel through the first and second sets of injector tips.